Flexible processing of metal sheets by cutting and/or forming can be performed by means of punching/forming machines. Some known machines permit various workpiece processing operations to be performed on the same machine tool. For example, sheet metal parts may be cut free from a sheet metal composite and forming operations may be performed on those sheet metal parts. An example of such a machine tool is the TruPunch® 5000 punching machine offered by Trumpf Werkzeugmaschinen GmbH+Co. KG which has mono-tool holders. The mono-tool holders support a single tool that includes a tool punch and a tool die. Further tools can be taken from a tool magazine and inserted as alternative tools into the mono-tool holders as and when required.
The mono-tool holders have a tool punch holder that can be raised and lowered by means of a hydraulic stroke drive, and a stationary tool die holder. A workpiece table serves to support a metal sheet that is to be processed. Workpiece processing is effected by lowering the tool punch holder together with a tool punch secured thereto onto the metal sheet supported on the workpiece table. The metal sheet is acted upon by the tool punch on the one side and by the tool die on the other.
Where a workpiece is subject to a forming operation, for example by roll-forming, in a region that was previously processed by a punching operation, the punched contour, produced by the punching operation, may change as a result of the forming operation, i.e., the punched contour may no longer correspond to the original contour produced by the punching operation.